1. Field of the Invention
This invention relates generally to seat supports for vehicles. More particularly, it relates to adjustable height seat supports for bicycles.
2. Background Art
Virtually all bicycles have adjustable seat posts for adjusting the bicycle seat to the rider""s desired position. Generally, seat posts slide inside the upright seat post receiving shaft of the bicycle frame and are locked into position with a clamp. It is essential to fix the seat in the proper position, in which maximum pedal leverage and energy efficiency are attained. Lower positions place excessive stress on the knees, and higher positions cause the rider to rock from side to side to reach the bottom of the pedal stroke, causing lower back strain.
Experienced bicycle riders change their body position based on terrain and road configuration, and often need additional seat heights for their different positions. For example, on steep descents, the rider needs a lower center of gravity to keep the back of the bicycle on the ground. Currently, when reaching a hill, the rider must stop the bicycle, loosen a clamp, change the seat height, and then tighten the clamp. This process is repeated whenever a seat height change is required. In addition to being time consuming, changing the seat height adds unnecessary and disruptive breaks to the ride.
In the U.S. Pat. No. 5,382,039, issued to Hawker, a spring-loaded seat support is described. The seat support disclosed by Hawker is adaptable to a bicycle frame and allows the bicycle seat to move up or down. However, the seat support does not provide a way to position and lock a bicycle seat into up or down positions, but rather serves as a shock absorbing seat support.
U.S. Pat. No. 510,993, issued to Riess, describes a spring-loaded seat support mechanism used to raise a seat from an initial depressed position. Before mounting the bicycle, the rider must manually adjust the seat to the lower position. The seat then automatically rises to the preferred height when the rider exerts pressure on the seat. Because the seat mechanism only works in one direction, it is not very useful for riders needing to raise and lower the seat without stopping the bicycle.
U.S. Pat. No. 2,644,504, issued to Vick, discloses a bicycle seat adjusting device that enables a rider to adjust the seat in both directions while riding. The device is relatively large, has many working parts and would be difficult to manufacture or fix. In addition, the device requires a polygonal seat post, rather than a standard cylindrical seat post.
An adjustable seat support that is capable of adjusting a seat height while a bicycle is in motion has been described in U.S. Pat. No. 4,150,851, issued to Cienfuegos. The seat support described is not readily transferable from one bicycle to another because the mechanism for adjusting the seat height is an integral part of the bicycle frame itself. In a later patent issued to Cienfuegos. U.S. Pat. No. 5,044,592, this problem is overcome with an independent seat replacement unit that consolidates all of the parts of the seat support. However, this design places the locking and positioning portion of the seat support at a position near the horizontal portion of the bicycle frame. Mountain bicycles are designed with low frames and long seat posts, such that there is significant distance between the horizontal portion of the bicycle frame and the bicycle seat. A locking and positioning portion of a seat support system attached near the horizontal frame portion of the bicycle can be very difficult for the rider to reach while the bicycle is in motion and may cause the rider to lose balance while attempting to change the seat position. Further, since the locking and positioning mechanism changes its location relative to the rider with each new seat position, the rider will have to search for location of the locking and positioning mechanism while riding, again making the seat adjustment procedure unsafe. Also, the seat support device described in U.S. Pat. No. 5,044,592 extends far into the upright seat post receiving shaft of the bicycle frame, which is not possible with all bicycle frame designs.
There are no existing patents that combined an adjustable seat post with suspension.
None of the prior art devices meets the requirements of adaptability, portability, and ease of use, wherein the seat support has a locking and positioning portion that is independent of the bicycle frame and remains in a constant, easily reachable position relative to the bicycle seat. Therefore, there is still need for a commercially viable option that satisfies the stated requirements.
Accordingly, it is a primary object of the present invention to provide an adjustable, telescoping seat support with a slidable, positioning tubular seat holder that moves up and down on a tubular seat post that is fixed to a bicycle frame. A bicycle seat that is attached to the slidable, positioning tubular seat holder is adjusted and locked in various height positions by a locking mechanism positioned substantially close to the attached bicycle seat. The present invention is well adapted for mountain bicycles, in which the seat is substantially higher than a horizontal cross bar portion of the bicycle frame.
It is a further object of the invention to provide an adjustable seat support that is not an integral part of the bicycle frame and that can easily be transferred from one bicycle to, another.
It is an additional object of the invention to provide an adjustable seat support with a small number of predetermined seat height positions, whereby the rider can switch quickly and easily between the predetermined seat height positions while riding.
It is another object of the present invention to provide a simple and adjustable seat support. wherein all of the adjustable and moving parts of the seat support are external to the bicycle frame, making repairs and maintenance to the seat support easier and less expensive.
It is a further object of the present invention to provide a seat support that is small and compact and that needs to be inserted only a short distance into the upright seat post receiving shaft of the bicycle frame in order to be safely secured to the bicycle frame.
It is further object of the invention to provide a seat support that has shock absorbing for the rider.
Lastly, it is an object of the present invention to provide an adjustable seat support for bicycles that is readily adapted to most standard mountain bicycle frames.
These objects and advantages are attained by providing an adjustable, telescoping seat support with suspension for attaching a seat, wherein an elongated tubular seat holder slidably moves up and down over an elongated tubular seat post. A positioning and locking portion are configured on the tubular seat holder. Because the positioning and locking portion of the seat support moves up and down with the seat, it remains within reach of a rider at a constant distance, regardless of the seat height position.
The telescoping action of the seat support is preferably provided by a coil spring positioned inside the tubular seat holder which provides an extending force on the inner stationary seat post and the tubular seat holder such that they tend to extend in a telescoping fashion in the absence of a compressing force or a locking mechanism. A downward force applied to the elongated tubular seat holder through an attached seat, wherein the downward force is sufficient to overcome the extending force of the spring, will lower the seat position. The position of the attached seat can then be fixed in a preferred position with a lock. Releasing the lock will allow the seat to rise due to the extending force provided by the spring.
In the most preferred embodiment of the current invention, the locking and positing portion of the seat support is a plunger locking and positioning portion. In the plunger locking and positing portion, there is a plunger attached to the elongated tubular seat holder in a direction substantially normal to the outer wall of the elongated tubular seat holder, and which extends through the wall of the elongated tubular scat holder through a plunger hole. The elongated tubular seat post has several plunger receptacles on the outer wall for receiving the plunger at different seat heights and locking the seat into a plurality of seat height positions. Preferably, the plunger is a spring-actuated plunger such that when the plunger is pulled in an outward direction, the elongated tubular seat holder is capable of sliding up or down over the outside wall of the elongated tubular seat post. Releasing the plunger then allows it to fit into one of the plunger receptacles and thus locks the seat into a new position.
In the most preferred embodiment of the seat support, the locking and positioning portion also includes a positioning stop that extends from an inner wall of the elongated tubular seat holder and fits into an elongated slot grooved in the outer surface of the elongated tubular seat post and extending up and down the seat post in the elongated direction. The positioning stop and the slot serve to limit the rotational position of the tubular seat holder between seat height positions during adjustment, and serve to define the upper and lower limit of the seat height adjustments. In a particular embodiment, the seat support is configured to have two plunger receptacles that correspond to these upper and lower limits.